Customizing the Commit Changes Dialog Follow

I am trying to write a wrapper plugin for the builtin subversion integration plugin in order to customize the Commit Changes dialog.
I figured out how to add to the additional options panel via the CheckinEnvironment.createAdditionalOptionsPanel but was wondering if it is possible to either add a button to the top of the dialog (near the other buttons like expand all, collapse all, etc.) or at the bottom of the dialog (under the Comment section).

Thanks!